Guest fails to boot about 75% of the time

Description

VB3.0.0, host and guest are both Ubuntu 9.04 64-bit.

About 75% of the time, when I attempt to boot the guest, the guest's boot process is interrupted before the GNOME desktop comes up. This only started happening once I upgraded to VB 3.0.0. My linux guest then sits at a command-line window, with text such as:

This morning I installed 3.0.8, installed the 3.0.8 guest additions, and again increased the virtual CPUs from 1 to 4. I have not yet seen the hang-on-boot bug, but did notice that bootups of my Ubuntu 9.04 guest are now taking in the range of 5 minutes versus the seconds it used to take.

Looking at the changelog for 3.0.8...which change do you suspect fixed the hang-on-boot error I previously was seeing when SMP was enabled?